UNIPROT:P14784 - FACTA Search

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Query: UNIPROT:P14784 (IL-2 receptor)
3,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Productive infection of cells by human immunodeficiency virus type 1 (HIV-1) is associated with the activation state of the cell and its obligatory expression of the interleukin-2 receptor (IL-2R), the latter providing a new target for antiviral therapy. A quantitative RNA-RNA hybridization assay is employed to detect production of HIV-1 RNA and to show that two IL-2 diphtheria toxin-related fusion proteins (DAB486IL-2 and its more potent, truncated form DAB389IL-2) inhibit HIV-1 RNA production in infected cells. A mutant form of DAB486IL-2 containing a single point mutation that inactivates the adenosine diphosphate ribosyltransferase activity of the toxin does not inhibit HIV RNA production, even though the molecule binds to the IL-2R. The active fusion proteins inhibit viral RNA replication in cells infected with HIV-1 clinical isolates as well as with a ZDV-resistant strain of HIV-1. These results indicate that IL-2 receptor-targeted fusion proteins can be utilized to inhibit HIV-1 replication effectively in infected human lymphocytes.
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PMID:Inhibition of HIV-1 RNA production by the diphtheria toxin-related IL-2 fusion proteins DAB486IL-2 and DAB389IL-2. 145 29

The radioresistance of lymphocytes increases after mitogenic stimulation, suggesting that a radiosensitive activation event contributes to the overall radiosensitivity of lymphocytes. We have sought to identify this activation event by determining the extent of activation of mitogen-stimulated lymphocytes previously exposed to growth-inhibiting doses of radiation. Mouse splenic lymphocytes were exposed to 0-15 Gy 137Cs radiation, and structural and functional damage were assayed. Although damage to cellular thiols and nonprotein thiols was modest, there was a significant loss of viability by 6 h as determined by uptake of propidium iodide (PI). Since cells did not die immediately after irradiation, the activation events which remained were evaluated. Growth-inhibiting doses of radiation left cells partially responsive to mitogen, in that cells were able to exit G0 phase, but they could progress no further into the cell cycle than G1a phase. It is important to note that assessment of viability by uptake of PI indicated substantial cell death after 15 Gy (45%, 6 h; 90%, 24 h); however, cell cycle analysis at 24 h indicated no significant decrease in progression from G0 to G1a phase. The LPS-stimulated response of B cells was more radiosensitive than the Con A-stimulated response of T cells. Further analysis of the Con A response indicated that production of interleukin-2 (IL-2) was unaffected, but expression of the IL-2 receptor was inhibited. Inhibition of poly-ADP-ribosylation and damage to lipids did not prevent the lack of mitogen responsiveness, since neither the ADP-ribose transferase inhibitor 3-aminobenzamide nor lipid radical scavengers had restorative effects on the mitogenic response. Nor was Con A-stimulated incorporation of [3H]thymidine restored with inhibitors of prostaglandin or leukotriene synthesis, suggesting that inhibition was due to direct effects on the Con A responders, and not indirect effects mediated by arachidonate metabolites. These results indicate that growth-inhibiting doses of radiation trigger the process in lymphocytes that culminates in apoptosis, yet leave the cells partially responsive to mitogenic stimuli.
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PMID:Residual activation events functional after irradiation of mouse splenic lymphocytes. 198 2

Anti-Tac(Fv)-PE40 is a recombinant single-chain immunotoxin containing the heavy and light variable regions of the anti-Tac monoclonal antibody fused to a mutant form of Pseudomonas exotoxin (PE). Anti-Tac binds to the p55 subunit of the human interleukin 2 (IL-2) receptor, and anti-Tac(Fv)-PE40 kills human or monkey cell lines that contain either the intact IL-2 receptor or its p55 subunit alone. To assess the usefulness of anti-Tac(Fv)-PE40 in treatment of IL-2 receptor-positive leukemia, we tested peripheral blood mononuclear cells from six patients with adult T-cell leukemia. In each of the six patients, anti-Tac(Fv)-PE40 was extremely cytotoxic to the malignant cells. Metabolic activity and sensitivity of the fresh cells improved when a small amount of IL-2 (10 units per ml) was present during incubation. The toxin concentration necessary to inhibit protein synthesis by 50% after 16-hr incubation of cells with immunotoxin varied from 1.6 to 16 ng/ml (2.5-25 x 10(-11) M). In every case, binding was by means of the Tac antigen because anti-Tac(Fv)-PE40 cytotoxicity was prevented by adding excess anti-Tac antibody. Moreover, anti-Tac alone or an inactive mutant of anti-Tac(Fv)-PE40 without ADP-ribosylation activity had very little cytotoxic activity. Peripheral blood mononuclear cells from normal controls, from a patient with Tac-negative leukemia, and from adult T-cell leukemia patients without significant peripheral blood involvement were not sensitive to anti-Tac(Fv)-PE40. These results indicate that anti-Tac(Fv)-PE40 is a potent cytotoxin against adult T-cell leukemia cells in vitro and warrants clinical testing.
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PMID:The recombinant immunotoxin anti-Tac(Fv)-Pseudomonas exotoxin 40 is cytotoxic toward peripheral blood malignant cells from patients with adult T-cell leukemia. 223 41

ADP ribosylation in the presence of cholera or pertussis toxin indicated the presence of G-proteins in Nb2 cell membranes. Two protein bands, with mol wt of 43.5K and 46.5K, were radiolabeled by cholera toxin, while a single protein (41.5K mol wt) was ADP ribosylated by pertussis toxin. Northern hybridization of total RNA from Nb2 cells with specific cDNA probes indicated the presence of mRNA transcripts encoding Gs, Gi2, Go, and, to a lesser extent, Gi3. A characteristic of receptors coupled to G-proteins is that their binding properties are regulated by guanine nucleotides. The binding of [125I]human GH to the lactogen receptor as well as the binding of [125I]IL-2 to the IL-2 receptor were decreased in a dose-dependent manner by GTP, GDP, and the analog guanosine 5'-O-(3-thiotriphosphate). GMP, however, had no effect. The addition of pyruvate kinase and phosphoenolpyruvate to regenerate GTP from GDP greatly increased the apparent potency of GTP. Cholera toxin inhibited PRL- and interleukin-2-stimulated DNA synthesis and cell proliferation in the Nb2 cells. In contrast, pertussis toxin had a differential effect on PRL- and IL-2-stimulated cells. Pertussis toxin, at an optimal concentration of 0.01 ng/ml, significantly enhanced the stimulatory effects of PRL on DNA synthesis (P less than or equal to 0.01; n = 9) and cell proliferation (P less than or equal to 0.05; n = 9) compared with the effect of PRL alone. However, at higher concentrations the toxin inhibited PRL-stimulated DNA synthesis and cell proliferation. Complete inhibition was achieved with 1000 ng/ml toxin. In contrast to the biphasic effect on PRL-stimulated cells, pertussis toxin was only weakly inhibitory to cells treated with IL-2. At the highest concentration tested, pertussis toxin (1000 ng/ml) inhibited IL-2-stimulated DNA synthesis and cell growth by only 30-35%. (Bu)2cAMP (IC50 = 0.019 mM) or methylxanthine (MIX; IC50 = 0.25 mM) also inhibited PRL-stimulated DNA synthesis. In the absence of mitogen, neither agent, from 0.0001-1 mM, had any effect on DNA synthesis. Similarly, IL-2-stimulated DNA synthesis in Nb2 cells was inhibited by (Bu)2cAMP (IC50 = 0.019 mM) or MIX (IC50 = 0.072 mM). However, MIX was approximately 3 times as potent in inhibiting the cell response to IL-2 as that to PRL. The susceptibility of Nb2 cells to both bacterial toxins suggests a role for G-proteins in regulating PRL- or IL-2-stimulated mitogenesis in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:G-proteins modulate prolactin- and interleukin-2-stimulated mitogenesis in rat Nb2 lymphoma cells. 246 72

Adjuvant arthritis in rats is a T-cell dependent "autoimmune" disease with close similarities to several forms of human arthritis. Injection of mycobacterial adjuvant leads to T-cell activation and proliferation, processes in which the de novo expression of the interleukin 2 (IL-2) receptor plays a pivotal role. The subsequent massive mononuclear cell infiltration of the joints ultimately results in complete joint destruction. Because activation of the helper/inducer subset of T lymphocytes is critical to the establishment of disease, we reasoned that IL2-PE40, a cytotoxic IL-2-Pseudomonas exotoxin fusion protein that targets the membrane-penetration and ADP-ribosylation domains of the toxin to cells bearing the IL-2 receptor, would be an effective and specific therapy. Adjuvant-injected rats were randomized to treatment with IL2-PE40, phosphate-buffered saline, or either of two control proteins related to IL2-PE40 but lacking either the receptor-binding moiety or an enzymatically active toxin domain and previously demonstrated to lack cytotoxicity in vitro. Intraperitoneal IL2-PE40 given before the establishment of overt clinical disease proved an effective and specific modifier of adjuvant arthritis by clinical, histological, and radiographic criteria. Our data suggest that IL2-PE40 may be effective in those diseases in which activated T-cells play an important role.
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PMID:Chimeric cytotoxin IL2-PE40 delays and mitigates adjuvant-induced arthritis in rats. 249 2

We have used protein engineering and recombinant DNA methodologies to genetically replace the eukaryotic cell receptor binding domain of diphtheria toxin with interleukin 2 (IL-2). The toxin-related T cell growth factor fusion gene has been cloned in Escherichia coli K12. Recombinant strains of E coli produce a 68,086 K hybrid toxin, IL-2 toxin that retains immunologic properties intrinsic to both its diphtheria toxin and IL-2 components. IL-2 toxin has been found to selectively inhibit protein synthesis in both human and murine T cell lines that bear high affinity IL-2 receptors, whereas the hybrid toxin is not active against cells that do not bear this receptor. The cytotoxic action of IL-2 toxin is specifically blocked by free IL-2 and monoclonal antibodies that bind to the p55 (Tac antigen) subunit of the high affinity IL-2 receptor. In addition, IL-2 toxin, like diphtheria toxin itself, must pass through an acidic compartment in order to deliver its adenosine diphosphate ribosyl transferase activity to the cytosol of target T cells. In a murine delayed type hypersensitivity (DTH) model system, we have shown that IL-2 toxin treatment induces a marked immunosuppression.
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PMID:Interleukin 2 toxin: a step toward selective immunomodulation. 312 10

In addition to the mobilization of neutrophils and monocytes, granulocyte-macrophage colony-stimulating factor (GM-CSF) also mobilizes lymphocytes into peripheral blood. We examined the ability of GM-CSF to induce the proliferation of purified human T cells (CD3+ CD4+ CD56- CD16- B1- MO2-) in two major aspects: (1) the mechanisms of GM-CSF interaction with interleukin-2 (IL-2) causing T-cell proliferation, and (2) the intracellular signals transmitted by GM-CSF in T lymphocytes. We observed that concentrations of GM-CSF between 0.01 ng/mL and 10 ng/mL had a synergistic effect with concentrations of IL-2 between 1 U/mL and 10 U/mL in stimulating T-cell proliferation. This effect of GM-CSF was maximal when it was added at the start of the culture. In situ hybridization showed the presence of mRNA for GM-CSF receptors in T cells. Further analysis showed that GM-CSF induced the expression of IL-2 receptor (IL-2R) on the surface of T lymphocytes. These events coincide with the ability of GM-CSF to increase the intracellular levels of both cyclic 3',5'-adenosine monophosphate (cAMP) and cyclic 3',5'-guanosine monophosphate (cGMP) in T cells, to increase the binding of (gamma-35S) GTP to T-cell membranes, and to enhance GTPase activity as determined by increased hydrolysis of 32P-GTP. IL-2 also induced IL-2R expression, cyclic nucleotide secretion, and G-protein activation. However, the presence of IL-2 reduced GM-CSF induction of these activities. Addition of antibodies to the alpha and beta subunits of IL-2R permitted the activation of G protein by GM-CSF even when IL-2 was present. Furthermore, GTP binding and GTPase activity induced by GM-CSF or IL-2 were inhibited by the addition of cholera toxin (CT), but not pertussis toxin (PT). Cumulatively, these results suggest that in T lymphocytes, receptors for GM-CSF or IL-2 may be coupled to the same CT-sensitive G protein, although other possibilities may exist. The role that G proteins play in mediating the intracellular signaling pathways induced by GM-CSF or IL-2 in human T cells is supported by adenosine diphosphate-ribosylation of a 44-kD or a 39-kD G protein in T-cell membranes by CT and PT, respectively.
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PMID:Priming effects of granulocyte-macrophage colony-stimulating factor are coupled to cholera toxin-sensitive guanine nucleotide binding protein in human T lymphocytes. 811 33

Biochemical, genetic and X-ray crystallographic analysis of diphtheria toxin have demonstrated that the native toxin is composed of three structural domains that function in an ordered fashion to intoxicate a eukoryotic cell. With the knowledge that, if delivered to the cytosol, a single molecule of the catalytic domain is lethal for the cell, we have used recombinant DNA methods to genetically replace the native toxin receptor binding domain with a series of growth factors. The resulting diphtheria toxin-related cytokine fusion proteins, or fusion toxins bind to their respective receptors, are internalized by receptor-mediated endocytosis, and efficiently eliminate target cell populations by the adenosine diphosphate ribosylation of elongation factor 2. Based upon the results of preclinical studies, DAB486IL-2, DAB389IL-2 and DAB389EGF have, or are in the process of being evaluated in Phase I/II clinical trials. To date, administration of the diphtheria toxin-based fusion proteins targeted toward the high affinity IL-2 receptor have been found to be safe, well tolerated, and capable of inducing remission in refractory hematologic malignancies.
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PMID:Targeting diphtheria toxin to growth factor receptors. 856 3

Fusion toxins are hybrid proteins consisting of peptide ligands linked through amide bonds to polypeptide toxins. The ligand directs the molecule to the surface of target cells and the toxin enters the cytosol and induces cell death. Ricin is an excellent candidate for use in fusion toxins because of its extreme potency, the extensive knowledge of its atomic structure and the lack of prior immunological exposure in patients. We synthesized a baculovirus transfer vector with the polyhedrin promoter followed sequentially from the 5' end with DNA encoding the gp67A leader sequence, the tripeptide ADP, IL-2 (interleukin-2), another ADP tripeptide and RTB (ricin toxin B chain) with lectin-site mutations W37S and Y248H. Recombinant baculovirus was generated in Sf9 insect cells and used to infect Sf9 cells. Recombinant IL-2-RTB[W37S/Y248H] protein (fusion protein of IL-2 with modifications W37S and Y248H) was recovered at high yields from day 6 insect cell supernatants, partially purified by affinity chromatography and reassociated with RTA (ricin toxin A chain). The fusion toxin was soluble, immunoreactive with antibodies to RTB, IL-2 and RTA and had a molecular weight of 80 kDa by SDS-PAGE. The molecule reacted poorly with asialofetuin, but bound strongly to IL-2 receptor based on selective cytotoxicity to IL-2 receptor bearing cells. The specific cytotoxicity could be blocked with IL-2 but not lactose. Thus, we report a novel targeted fusion toxin protein with full biological activity.
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PMID:Characterization of a ricin fusion toxin targeted to the interleukin-2 receptor. 893 Nov 31

Genetic engineering has led to the development of fusion protein toxins, which are targeted effector molecules that combine a targeting ligand such as a growth factor with a cytocidal moiety such as a plant or bacterial toxin. The first genetically constructed family of fusion proteins used diphtheria toxin as the toxophore for receptor-binding domain substitution. Diphtheria toxin consists of three domains: an enzymatically active adenosine diphosphate (ADP) ribosyltransferase domain, a hydrophobic transmembrane domain, and a C-terminal receptor-binding domain. Introduction of the enzymatically active domain into the cytosol via receptor-mediated endocytosis results in inhibition of protein synthesis by ADP ribosylation of elongation-factor 2. DAB(486)IL-2, in which the native receptor-binding domain of diphtheria toxin was replaced with the full-length interleukin-2 (IL-2) gene, was capable of intoxicating high-affinity IL-2 receptor-bearing cells in vitro with an IC(50) of 10(-10) M; whereas, cells lacking the full component of the high-affinity IL-2 receptor (p55, p75, p64) were relatively resistant (IC(50) of 10(-8) M). Because of a short in vivo half-life of DAB(486)IL-2, efforts to reengineer the molecule were undertaken, leading to the DAB(389)IL-2 construct, which had a twofold to threefold higher Kd than DAB(486)IL-2 and a longer half-life, resulting in a tenfold increase in potency. Thus far, the clinical activity of both IL-2 chimeric fusion toxins has been similar, with the DAB(389)IL-2 molecule displaying more favorable pharmacokinetics.
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PMID:DAB(389)IL-2 (denileukin diftitox, ONTAK): a new fusion protein technology. 1170 60

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